arXiv subjects
Publications and source records attributed to Seung-Man Yang.
We use digital holographic microscopy and Mie scattering theory to simultaneously characterize and track individual colloidal particles. Each holographic snapshot provides enough information to measure a colloidal sphere's radius and refractive index to within 1%, and simultaneously to measure its three-dimensional position with nanometer in-plane precision and 10 nanometer axial resolution.
Dissolving armored bubbles stabilize with nonspherical shapes by jamming the initially Brownian particles adsorbed on their interfaces. In a gas-saturated solution, these shapes are characterized by planar facets or folds for decreasing ratios of the particle to bubble radii. We perform numerical simulations that mimic dissolution, and show that the faceted shape represents a local minimum of energy during volume reduction. This minimum is marked by the vanishing of the Laplace overpressure $ΔP$, which together with the existence of a $V$-interval where $dΔP/dV>0$ guarantees stability against dissolution. The reduction of $ΔP$ is due to the saddle-shape deformation of most of the interface which accompanies the reduction in the mean curvature of the interface.